Heavy alcohol recycling system and method for EO and EC devices

Abstract

The invention discloses a heavy alcohol recycling system and recycling method for EO and EC devices, heavy alcohol of the EO device and heavy alcohol of the EC device are converged and then are sequentially dried through a dehydrating tower, MEG refining is performed through an MEG refining tower to obtain an MEG product, DEG refining is performed through a DEG refining tower to obtain a DEG product, and further refining and recycling of MEG and DEG in the EO device and the EC device are effectively realized. The recovery efficiency is improved, and the emission of the heavy alcohol hazardous waste and the hazardous waste treatment cost are reduced.

Description

Technical Field

[0001] The invention relates to the field of heavy alcohol refining and purification, and in particular to a heavy alcohol refining system and a refining method for EO and EC devices. Background Art

[0002] In the existing technology, the operation of the EG (ethylene glycol) refining system of the EC (epichlorohydrin) unit produces some heavy alcohols, whose main components are DEG (diethylene glycol), MEG (monoethylene glycol) and other heavy components, accounting for approximately 88.43%, 6.58% and 4.99% respectively. They are currently treated as hazardous wastes, and the treatment cost is about 970 yuan / ton. The EG refining system of EO (ethylene oxide) also produces some heavy alcohols, and the main components of the heavy alcohols of the EC unit and the EO unit are similar. At present, the heavy alcohols of the EC unit are treated as hazardous wastes, and the heavy alcohol recycling device of the EO unit has the defect of low recovery rate, and the existing technology does not yet have a heavy alcohol recycling system combining the EC unit and the EO unit. Therefore, it is urgent to design a heavy alcohol recovery device shared by the EO unit and the EC unit to improve the recovery rate of DEG and MEG and reduce hazardous waste emissions and hazardous waste treatment costs. Summary of the invention

[0003] In view of the deficiencies in the prior art, the technical problem to be solved by the present invention is to provide a heavy alcohol recycling system and recycling method for EO and EC devices with high DEG and MEG recovery rates, thereby reducing hazardous waste emissions and hazardous waste treatment costs.

[0004] To solve the above problems, the present invention provides the following technical solutions: A heavy alcohol recycling system for EO and EC devices comprises heavy alcohol from EC devices and a crude ethylene glycol tank for storing heavy alcohol from EO devices, wherein a discharge end of the heavy alcohol from EC devices is connected in parallel with a pipeline 1 and a pipeline 2, wherein the pipeline 1 is connected to the heavy alcohol tank, and the pipeline 2 is connected to the crude ethylene glycol tank; the discharge end of the crude ethylene glycol tank is connected to a feed end of a dehydration tower through a crude ethylene glycol pump, the bottom discharge end of the dehydration tower is connected to a feed end of a MEG refining tower through a dehydration tower kettle liquid pump, and the top discharge end of the MEG refining tower is sequentially connected to a MEG product intermediate tank and a MEG product tank; the bottom discharge end of the MEG refining tower is connected to a DEG refining tower through a MEG refining tower kettle liquid pump, the top discharge end of the DEG refining tower is sequentially connected to a DEG product intermediate tank and a DEG product tank, and the bottom discharge end of the DEG refining tower is connected to the heavy alcohol tank through a DEG refining tower kettle liquid pump.

[0005] The technical solution of the present invention also includes that a dehydration tower reboiler is also provided at the bottom discharge end of the dehydration tower, and the discharge end of the dehydration tower reboiler is connected to the dehydration tower reboiler feed port on the side wall of the dehydration tower; the bottom discharge end of the MEG refining tower is also connected to the MEG refining tower reboiler, and the discharge end of the MEG refining tower reboiler is connected to the MEG refining tower reboiler feed port located on the side wall of the MEG refining tower; the bottom discharge end of the DEG refining tower is also connected to the DEG refining tower reboiler, and the discharge end of the DEG refining tower reboiler is connected to the DEG refining tower reboiler feed port located on the side wall of the DEG refining tower.

[0006] The technical solution of the present invention also includes that the discharge end of the MEG refining tower bottom liquid pump is connected in parallel with the feed ends of pipeline three and pipeline four, the discharge end of pipeline three is connected with the feed end of the DEG refining tower, the discharge end of the DEG refining tower bottom liquid pump is also connected with the feed end of pipeline four, the discharge end of pipeline four is connected with the heavy alcohol tank, and a bottom cooler is provided on pipeline four.

[0007] The technical solution of the present invention also includes that the top discharge end of the DEG refining tower is connected to the feed end of the circulation pipeline, and the discharge end of the circulation pipeline is connected to the feed end of the MEG refining tower.

[0008] The technical solution of the present invention also includes that a MEG tower condenser is provided at the top of the MEG refining tower, the MEG tower condenser and the top of the dehydration tower are both connected to an injection system, and the injection system is connected to a sewage pool.

[0009] The second object of the present invention is to provide a recycling method for the heavy alcohol recycling system for the above-mentioned EO and EC devices, comprising the following steps: (1) Part of the heavy alcohol produced by the EC unit is transported to the heavy alcohol tank through pipeline 1, and the other part is transported to the crude ethylene glycol tank for storing the heavy alcohol of the EO unit through pipeline 2; (2) The heavy alcohol stored in the crude ethylene glycol tank is first dried by a dehydration tower. The dehydrated heavy alcohol enters the MEG refining tower from the bottom discharge port of the dehydration tower through the dehydration tower kettle liquid pump for MEG refining. The obtained MEG product enters the MEG product tank for storage through the MEG product intermediate tank, thus realizing MEG recovery; (3) The bottom liquid of the MEG refining tower is transported to the DEG refining tower through the MEG refining tower bottom liquid pump for DEG refining. The obtained DEG product enters the DEG product tank for storage through the DEG product intermediate tank to achieve DEG recovery; (4) The bottom liquid of the DEG refining tower is transported to the heavy alcohol tank through the DEG refining tower bottom liquid pump and stored as hazardous waste.

[0010] In order to improve the recovery rate of MEG and DEG, the technical solution of the present invention also includes that a sensitive plate is provided in the MEG refining tower, the temperature of the sensitive plate is set to 139°C-140°C, and the temperature of the middle and lower sections in the DEG refining tower is set to 142°C.

[0011] The technical solution of the present invention also includes that part of the bottom liquid of the MEG refining tower in step (3) is transported to the DEG refining tower through pipeline three for DEG refining, and the other part is transported to the heavy alcohol tank through pipeline four.

[0012] Furthermore, the technical solution of the present invention also includes that the bottom liquid of the DEG refining tower and the bottom liquid of the MEG refining tower in pipeline 4 are cooled by a bottom cooler before entering the heavy alcohol tank.

[0013] The technical solution of the present invention also includes that the material separated by evaporation at the top of the DEG refining tower is transported to the MEG refining tower through a circulation pipeline for circulating refining of MEG.

[0014] The beneficial effects of the present invention are: Compared with the prior art, the purpose of the present invention is to provide a heavy alcohol recycling system and recycling method for EO and EC devices with high DEG and MEG recovery rates, thereby reducing hazardous waste emissions and hazardous waste treatment costs. To achieve the above-mentioned technical effects, the present application provides a heavy alcohol recovery device and recovery method shared by an EO device and an EC device. After the heavy alcohol of the EO device and the heavy alcohol of the EC device are combined, they are dried in turn through a dehydration tower, and then the MEG is refined through a MEG refining tower to obtain a MEG product, and then the DEG is refined through a DEG refining tower to obtain a DEG product, thereby effectively realizing the refining and recovery of heavy alcohols in the EO device and the EC device, improving the recovery efficiency, and reducing the emission of heavy alcohol hazardous waste and the cost of hazardous waste treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0016] Figure 1 It is a schematic diagram of the structure of the heavy alcohol recycling system for EO and EC devices in a specific implementation manner.

[0017] Among them, 1 is a crude ethylene glycol tank, 2 is pipeline one, 3 is pipeline two, 4 is a heavy alcohol tank, 5 is a crude ethylene glycol pump, 6 is a dehydration tower, 7 is a dehydration tower bottom liquid pump, 8 is a MEG refining tower, 9 is a dehydration tower reboiler, 10 is a MEG product intermediate tank, 11 is a MEG product tank, 12 is a MEG refining tower bottom liquid pump, 13 is a DEG refining tower, 14 is a MEG refining tower reboiler, 15 is a MEG tower condenser, 16 is an injection system, 17 is a sewage pool, 18 is a DEG product intermediate tank, 19 is a DEG product tank, 20 is a DEG refining tower bottom liquid pump, 21 is a DEG refining tower reboiler, 22 is a circulation pipeline, 23 is a pipeline three, 24 is a pipeline four, and 25 is a bottom cooler. DETAILED DESCRIPTION

[0018] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0019] In the description of the present invention, it should be understood that the terms "center", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only intended to simplify the description of the present invention, rather than to indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0020] As can be seen from the accompanying drawings, a heavy alcohol recycling system for EO and EC devices includes heavy alcohol from an EC device and a crude ethylene glycol tank 1 for storing heavy alcohol from the EO device. The discharge end of the heavy alcohol from the EC device is connected in parallel with pipeline 1 2 and pipeline 2 3. Pipeline 1 2 is connected to the heavy alcohol tank 4, and pipeline 2 3 is connected to the crude ethylene glycol tank 1.

[0021] The discharge end of the crude ethylene glycol tank 1 is connected to the feed end of the dehydration tower 6 through the crude ethylene glycol pump 5, and the bottom discharge end of the dehydration tower 6 is connected to the feed end of the MEG refining tower 8 through the dehydration tower kettle liquid pump 7. The bottom discharge end of the dehydration tower 6 is also provided with a dehydration tower reboiler 9, and the discharge end of the dehydration tower reboiler 9 is connected to the dehydration tower reboiler feed port on the side wall of the dehydration tower.

[0022] The top discharge end of the MEG refining tower 8 is connected to the MEG product intermediate tank 10 and the MEG product tank 11 in sequence; the bottom discharge end of the MEG refining tower 8 is connected to the DEG refining tower 13 through the MEG refining tower kettle liquid pump 12, and the bottom discharge end of the MEG refining tower 8 is also connected to the MEG refining tower reboiler 14, and the discharge end of the MEG refining tower reboiler 14 is connected to the MEG refining tower reboiler feed port located on the side wall of the MEG refining tower 8. A MEG tower condenser 15 is provided on the top of the MEG refining tower 8, and the MEG tower condenser 15 and the top of the dehydration tower 6 are both connected to the injection system 16, and the injection system 16 is connected to the sewage pool 17.

[0023] The top discharge end of the DEG refining tower 13 is connected to the DEG product intermediate tank 18 and the DEG product tank 19 in sequence, the bottom discharge end of the DEG refining tower 13 is connected to the heavy alcohol tank 4 through the DEG refining tower bottom liquid pump 20, and the bottom discharge end of the DEG refining tower 13 is also connected to the DEG refining tower reboiler 21, and the discharge end of the DEG refining tower reboiler 21 is connected to the feed port of the DEG refining tower reboiler located on the side wall of the DEG refining tower 13. The top discharge end of the DEG refining tower 13 is connected to the feed end of the circulation pipeline 22, and the discharge end of the circulation pipeline 22 is connected to the feed end of the MEG refining tower 8.

[0024] The discharge end of the MEG refining tower bottom liquid pump 12 is connected in parallel with the feed ends of pipeline three 23 and pipeline four 24, the discharge end of pipeline three is connected with the feed end of the DEG refining tower, the discharge end of the DEG refining tower bottom liquid pump 20 is also connected with the feed end of pipeline four 24, the discharge end of pipeline four 24 is connected with the heavy alcohol tank 4, and a bottom cooler 25 is provided on pipeline four 24.

[0025] A recycling method for a heavy alcohol recycling system for EO and EC devices comprises the following steps: (1) Part of the heavy alcohol produced by the EC unit is transported to the heavy alcohol tank 4 through pipeline 1 2, and the other part is transported to the crude ethylene glycol tank 1 for storing the heavy alcohol of the EO unit through pipeline 2 3.

[0026] (2) The heavy alcohol stored in the crude ethylene glycol tank 1 is first dried by a dehydration tower 6. The dehydrated heavy alcohol enters a MEG refining tower 8 from the bottom discharge port of the dehydration tower 6 via a dehydration tower bottom liquid pump 7 for MEG refining. The obtained MEG product enters a MEG product tank 11 for storage via a MEG product intermediate tank 10, thereby realizing MEG recovery. A sensitive plate is provided in the MEG refining tower 8, and the temperature of the sensitive plate is set to 139°C-140°C.

[0027] (3) A portion of the bottom liquid of the MEG refining tower 8 is transported to the DEG refining tower 13 through pipeline three 23 for DEG refining, and the other portion is transported to the heavy alcohol tank 4 through pipeline four 24. The temperature of the middle and lower sections in the DEG refining tower 13 is set to 142°C, and the obtained DEG product enters the DEG product tank 19 for storage through the DEG product intermediate tank 18 to achieve DEG recovery. The material separated by evaporation at the top of the DEG refining tower 13 is transported to the MEG refining tower 8 through the circulation pipeline 22 for the circulation refining of MEG.

[0028] (4) The bottom liquid of the DEG refining tower 13 is transported to the heavy alcohol tank 4 by the DEG refining tower bottom liquid pump 20 and stored as hazardous waste. The bottom liquid of the DEG refining tower 13 and the bottom liquid of the MEG refining tower 8 in the pipeline 4 are cooled by the bottom cooler 25 before entering the heavy alcohol tank 4.

[0029] Through the above-mentioned heavy alcohol recycling device and recycling method, based on the applicant's existing production capacity, taking the recycling amount of heavy alcohol of the EC device as an example, it is calculated that the recycling amount of heavy alcohol of the EC device is about 4 tons / day, and all of its MEG is recycled. Calculated based on about 50% (wt) DEG being recycled, the production cost is saved by about (MEG / DEG product income + saving of heavy alcohol hazardous waste treatment cost) about 12,200 yuan / day, saving 4.16 million yuan throughout the year (calculated based on 340 days of stable production throughout the year), and at the same time greatly reducing the cost of treating hazardous waste heavy alcohol. The specific calculation is as follows: The recycling income of industrial-grade MEG products (market unit price is about 4,100 yuan / ton) is approximately: 4×6.58%×4100≈1,080 yuan / day.

[0030] The recovery income of DEG products (market unit price is about 5,200 yuan / ton) is approximately: 4×88.43%×50%×5200≈9,197 yuan / day.

[0031] Saving heavy alcohol hazardous waste (treatment cost is about 970 yuan / ton) treatment cost is approximately: (4×6.58%+4×88.43%×50%)×970≈1970 yuan / day.

[0032] Full year: (based on a 340-day budget) (1080+9197+1970)×340 / 10000≈4.16 million yuan.

[0033] The recycling method of the heavy alcohol recycling system for EO and EC devices of the present application effectively improves the recovery rate of heavy alcohol, effectively reduces the cost of treating hazardous waste heavy alcohol and significantly saves production costs, and reduces hazardous waste emissions, with significant economic and environmental benefits.

[0034] Although the present invention has been described in detail by referring to the accompanying drawings and in combination with the preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, a person of ordinary skill in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and these modifications or substitutions shall be within the scope of the present invention. Any person of ordinary skill in the art who is familiar with the present invention may easily think of changes or substitutions within the technical scope disclosed by the present invention, and all of these shall be within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of protection of the claims.

Claims

1. A heavy alcohol recycling system for EO and EC devices, characterized by: It comprises heavy alcohol of EC device and crude ethylene glycol tank for storing heavy alcohol of EO device, the discharge end of heavy alcohol of EC device is connected with pipeline 1 and pipeline 2 in parallel, pipeline 1 is connected with heavy alcohol tank, pipeline 2 is connected with crude ethylene glycol tank; the discharge end of crude ethylene glycol tank is connected with the feed end of dehydration tower through crude ethylene glycol pump, the bottom discharge end of dehydration tower is connected with the feed end of MEG refining tower through dehydration tower kettle liquid pump, the top discharge end of MEG refining tower is connected with MEG product intermediate tank and MEG product tank in sequence; the bottom discharge end of MEG refining tower is connected with DEG refining tower through MEG refining tower kettle liquid pump, the top discharge end of DEG refining tower is connected with DEG product intermediate tank and DEG product tank in sequence, the bottom discharge end of DEG refining tower is connected with heavy alcohol tank through DEG refining tower kettle liquid pump.

2. The heavy alcohol recycling system for EO and EC devices according to claim 1, characterized in that: The bottom discharge end of the dehydration tower is also provided with a dehydration tower reboiler, and the discharge end of the dehydration tower reboiler is connected to the dehydration tower reboiler feed port on the side wall of the dehydration tower; the bottom discharge end of the MEG refining tower is also connected to the MEG refining tower reboiler, and the discharge end of the MEG refining tower reboiler is connected to the MEG refining tower reboiler feed port located on the side wall of the MEG refining tower; the bottom discharge end of the DEG refining tower is also connected to the DEG refining tower reboiler, and the discharge end of the DEG refining tower reboiler is connected to the DEG refining tower reboiler feed port located on the side wall of the DEG refining tower.

3. The heavy alcohol recycling system for EO and EC devices according to claim 1, characterized in that: The discharge end of the MEG refining tower bottom liquid pump is connected in parallel with the feed ends of pipeline three and pipeline four, the discharge end of pipeline three is connected with the feed end of the DEG refining tower, the discharge end of the DEG refining tower bottom liquid pump is also connected with the feed end of pipeline four, the discharge end of pipeline four is connected with the heavy alcohol tank, and a bottom cooler is provided on pipeline four.

4. The heavy alcohol recycling system for EO and EC devices according to claim 1, characterized in that: The discharge end at the top of the DEG refining tower is connected to the feed end of a circulation pipeline, and the discharge end of the circulation pipeline is connected to the feed end of the MEG refining tower.

5. The heavy alcohol recycling system for EO and EC devices according to claim 1, characterized in that: A MEG tower condenser is arranged at the top of the MEG refining tower. The MEG tower condenser and the top of the dehydration tower are both connected to the injection system, and the injection system is connected to a sewage pool.

6. A recycling method for a heavy alcohol recycling system for EO and EC devices as claimed in any one of claims 1 to 5, characterized in that: The following steps are involved: Part of the heavy alcohol produced by the EC unit is transported to the heavy alcohol tank through pipeline 1, and the other part is transported to the crude ethylene glycol tank storing the heavy alcohol of the EO unit through pipeline 2; The heavy alcohol stored in the crude ethylene glycol tank is first dried by a dehydration tower. The dehydrated heavy alcohol enters the MEG refining tower from the bottom discharge port of the dehydration tower through the dehydration tower kettle liquid pump for MEG refining. The obtained MEG product enters the MEG product tank for storage through the MEG product intermediate tank to achieve MEG recovery. The bottom liquid of the MEG refining tower is transported to the DEG refining tower through the MEG refining tower bottom liquid pump for DEG refining, and the obtained DEG product enters the DEG product tank for storage through the DEG product intermediate tank to realize DEG recovery; The bottom liquid of the DEG refining tower is transported to the heavy alcohol tank via the DEG refining tower bottom liquid pump and stored as hazardous waste.

7. The method for recycling heavy alcohol for EO and EC devices according to claim 6, characterized in that: A sensitive plate is provided in the MEG refining tower, and the temperature of the sensitive plate is set at 139°C-140°C. The temperature of the middle and lower sections in the DEG refining tower is set at 142°C.

8. The recycling method of heavy alcohol for EO and EC devices according to claim 6, characterized in that: Part of the bottom liquid of the MEG refining tower in step (3) is transported to the DEG refining tower through pipeline three for DEG refining, and the other part is transported to the heavy alcohol tank through pipeline four.

9. The method for recycling heavy alcohol for EO and EC devices according to claim 8, characterized in that: The bottom liquid of the DEG refining tower and the bottom liquid of the MEG refining tower in pipeline 4 are cooled by the bottom cooler before entering the heavy alcohol tank.

10. The method for recycling heavy alcohol for EO and EC devices according to claim 6, characterized in that: The material separated by evaporation at the top of the DEG refining tower is transported to the MEG refining tower through a circulation pipeline for circulating refining of MEG.

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